Aerial navigational signaling system



Sept. 21, 1937. A. M L. NICOLSON 2,093,541

AERIAL NAVIGATIONAL SIGNALING SYSTEM Original Filed June 28, 1950 5 Sheets-Sheet 1 AlExandEr M L. EH11 NiE [I15 [I11 'Sept. 21, 1937. A, MCL, NI L S N 2,093,641

AERIAL NAVIGATIONAL SIGNALING SYSTEM Original Filed June 28, 1950 5 Sheets-Sheet 2 /50 ELLE-.-

V WF 000 jwo UN 5 EE- 7 EG E Alexander MELEEIH NiEDlS I111 AERIAL NAVIGATIONAL SIGNALING SYSTEM Original Filed June 28,1930 3 Sheets-Sheet 3 Pic-21.15 EE. l Fics l5 Lav :hwwnto c Alexan I121 M L. EEm Nil: [115 [111 Patented Sept. 21, 1937 AERIAL NAVIGATIONAL SIGNALING SYSTEM Alexander McLean Nicolson, New York, N. Y., as-

signor to Communication Patents, Inc., New York, N. Y., a corporation of Delaware Original application June 28, 1930, Serial No. 464,480. Divided and this application August 4, 1931, Serial No. 554,967

2 Claims. ((11. 177-352) This invention relates to electrical signaling systems, and particularly to a method of and means for signaling from ground to aircraft in flight, and between aircraft and land stations.

5 This application is a division of Patent No.

1,977,198 of October, 16, 1934.

An object of this invention is to enable aircraft in flight to determine its geographical position when the vision of the pilot is obscured.

Another object of the invention is to enable aircraft to determine its altitude position during 1 periods of low or non-visibility.

Another object of the invention is to transmit characteristic signals toenable aircraft to determine its position at any time during flight.

For night flying or for aerial navigation during fogs, clouds and the like, itis extremely desirable to have means for determining the exact position of the aircraft, both as to altitude and location. It is especially desirable to determine whether or not aircraft is over land or water, also the nature of the land over which it is flying, such as mountainous regions, forest or prairie sections. The present invention enables a pilot to determine his position with respect to any particular landing field, and permits him to follow a pre-arranged course during nonvisibility, and to adjust his altitude of flight so as not to come in contact with .power lines,

mountains or high buildings.

A particular feature of this invention is the use of a trailing antenna, which may be adjusted with respect to the sending stations during flight to obtain directional effects.

just along trailing antenna enables an observer to determine, not only the direction of the signals being received, but to distinguish between certain types of signals being transmitted. The antenna is adjusted by means of a trailer plane or kite.

This invention contemplates the transmission of characteristic signals, such as differences in amplitude and differences in frequencies at certain strategic broadcast points. A certain definite area on the ground may transmit various signals characterized by frequency and amplitude, such that by varying the adjustment of the aerial by the, aircraft observer, the pilot may determine his position and be directed along a safe course both as to height above ground and direction of flight. The different frequencies at the different locations may serve as indicators of geographical positions while the different am- 55 plitudes may indicate the direction of flight such The ability to adas increasing amplitudes indicating one direction and decreasing amplitudes another direction.

To distinguish between the land surface such as land and water, trees and plain, a microphone is provided in the small trailing kite or plane, to 5 the diaphragm of which is attached long feeler wires of varying lengths, which are adapted to drag along the ground surface. The frictional signals produced in the wires are characteristic of the material'over which the feelers are pass- 10 ing, the signals being transmitted to the observer in the plane for differentiation. For instance, when the plane is passing ovewater, a definite characteristic sound is transmitted by the microphone to the receivers, while an en- 15 tirely different sound is obtained when the feelers are passing or dragging over a surface comprised of stones or trees. A small amount of practice in observing the characteristics of the sounds when the objects producing them are 20 known, will soon permit an observer to imme diately determine the character of the surface over which he is passing. The trailing plane may be drawn into the main aircraft when not required. 5

The invention will be more fully understood by reference to the accompanying drawings, in which:

Figure 1 is a perspectiveview of one embodiment of the invention; 30 Fig. 2 is a cross-sectional view of a trailing plane with its interior mechanism and external circuits; v

Fig. 3 is a modification of the plane of Fig. 2.-

Figs. 4 and. 5 show means for transmitting 35 characterized signals along a transmission line;

Figs. 6 to 19, inclusive, show various types of means which may be distributed along high power transmission lines or independent systems for the transmission of characterized signals 40 over definite areas; and

Fig. 20 is a circuit drawing'of a transmitting and receiving system for use with a power transmission system.

Referring specifically to Fig. 1, an aeroplane 45 in flight has a trailing kite or plane 5 attached thereto by a cable 4, while the plane 5 has feeler antennae 6 hanging from its lower side. The solid and dotted line drawings indicate two posi- 50 tions which the trailing plane may have with the aeroplane in the same position. In the second or dotted line position, it is observed that the feeler antennae is in contact with the earth,

for transmitting to an observer in the plane the nature of the land over which the antennae is being drawn.

Referring to Fig. 2, a cross-section of one form of trailer is shown 'with its adjusting cable and control circuits. The plane I2 may be drawn up into the aeroplane by means of a. sheave 8 and a cable 9. Parallel with the sheave 9 are transmission wires l0 and I I, which may be connected to slip rings mounted on the sheave for the transmission of energy from and to the kite plane in any well known manner. The wires l0 and Il may also be enclosed within the cable 9, or they may be of such size that they serve as a cable. The plane I2 is equipped with a wind mill propeller H which drivesa screw l5 located near the terminal of a drive shaft [6 when being drawn through the air by the main aircraft. Normally, the screw is out of contact with a gear l8 which is fastened to a wing l9 which may be tilted by the turning of the gear. That is, when the wing is tilted downwards, the trailing plane will take the position shown by the dotted line sketch in Fig. 1, and if tilted backward, will take the position shown by the solid line sketch. The power for tilting the plane is obtained by'the propeller M. The worm I5 is meshed with the gear I8 by energizing a coil 22 over conductors l0 and II from a source of current 23 located in the plane. In fact all the apparatus is permanently located in the main craft with the exception of the trailer and connecting wires. Upon energization of the coil, a magnetic armature 24 israised meshing the gears and tilting the wing forward, which forces the aeroplane to a lower level. A key 26 controls the energization of the coil 22. The key 26 may remain closed and when the wing has reached its tilting limit, it will stop the propeller I 4, as the propeller generates slightly more than sufficient power to drive the wing forward. The wing will be maintained in the forward position by the propeller thrust. When it is desired to raise the trailer to an upper level comparable to that of the main craft, the key 26 is opened, the worm is released from the gear l8, and the force of the air passing the trailer will lift the wing I 9, and force it backward to a limiting position, which will raise the trailer.

Located in the main plane is a receiver 30 and an amplifier 3|, each of which is provided with head phones 32 and 33, respectively, connected to the lines l0 and II through blocking condensers 35. These units may'actually comprise a single receiving system with switches for switching the single wire input line 36 to the double wire input. In the present embodiment, amplifier 3| is employed to amplify signals from a microphone or pick-up 38 located in the trailing plane, the microphone having a diaphragm 39 to which is connected trailing or feeler wires 40 represented by Ii in Fig. 1. Frictional vibrations generated in the wires 40 are changed into electrical vibrations by the microphone 38, and are transmitted over the wires Ill and l I, to amplifier 3| for detection. The wires 40 may be terminated in metal discs I, to increase the efliciency and to act as sinkers for the feeler wires. The receiver 30 is connected to either one of the conductors l0 and I I, which serve as the antenna for picking up transmitted signals from land or aircraft radiating stations.

In Fig. 3 another means of adjusting the plane to take difierent altitudes of flight with respect to the main plane is shown. In this modification no wind mill propeller is required. since a coil 42 operates a rack 43 to tilt a wing 44 associated with a gear 45. A spring 46 may revert the wing to its opposite position, or the action of the passing air may perform this function. The coil 42 may be energized from a source of power within the plane over the connecting wires, as shown in Fig. 2.

During operation of the receiver to detect certain signals being transmitted along the route, the kite plane is raised or lowered to determine the relative strength of signals being received. At the same time, the feelers are brought in contact with the land or water, as the case may be, and the determination of the nature thereof is made. During periods of visibility, the trailermay be brought into the aeroplane by winding the cable 9 on the sheave 8. Even in cases of visibility, it may be desirable to transmit or receive communication signals from the plane, and this may be readily accomplished by dropping the antenna. During these periods the trailer may be adjusted to a position to receive maximum signal strength of radiation in the case of transmitting.

The broadcasting of signals to an aeroplane in flight may be accomplished by placing high frequency on power lines, or on lines strung especially for the purpose. In Fig. 4, the method shown is by placing various numbers of turns 50 either in the power transmission conductors themselves. or in special antennae circuits, while Fig. 5 shows another arrangement of turns Si in such lines. The various turns are placed at unequal intervals along the lines, the arrangement of different strength radiations in a particular pattern characterizing a definite geographical area. The pilot or observer in the aircraft having previous knowledge of the characterizations of areas according to their location, will be enabled to immediately know his position. The signals may be high frequency currents superimposed upon the power line currents or generated from the power line currents at points along the line, and

may be characterized in various ways such as by continuous waves or impulses in a definite order.

Figs. 6 and 7 show means for mounting coils 53 and 54 on transmission poles,. 5.5 and 56, respectively, for radiating the high frequency signaling currents. These coils may be placed'in a plane perpendicular to the surface of the earth, or in a plane parallel therewith. In themodiflcation of Figs. 4 to 7, inclusive, the electro-magnetic energy radiated into the surrounding area at the difl'erent points along the line is varied in direction and strength in accordance with the number of turns of each coil and the position of their magnetic axes, the energy drop between points being negligible.

Fig. 8 shows means of producing a characteristic frequency radiation by. having an are or spark gap 59 in series with a variable condenser 60 and resistance 6| connected across the power conductors for the purpose of tuning the arc to a particular harmonic produced byit, which will be radiated by the line conductors of the previous figures. This unit may be mounted on a power line pole or mast 62 in a casing 33. In this instance no high frequency is required to be superimposed upon the power current, as the power current itself maybe utilized to produce the discharge at the gap 59.

Figs. 9 and 10 show means for radiating high frequency currents transmitted over the line by use of tuned circuits 65 and 66, which may be connected to ground as shown and have a vertical aerial 61, as shown in Fig. 10. In Fig. 9 radiation is accomplished through use of the power line itself while in Fig. 10 both the power line and the vertical aerial 61 cooperate with one another. These units may be distributed along the line, as disclosed in Figs. 4 and 5, for producing various amplitudes, the units receiving their energy from high frequency transformers 69 and 10. That is, certain superimposed high frequency energy will be shunted to ground at these points depending on thetuning of circuits 65 and 66, thus varying the uniform decrease or increase of the electro-magnetic field along the power line caused by power line impedance. At these points the change in the strength of the radiated field above the line will be abrupt.

In Fig. 11 an oscillator 12 supplied from the current transmitted along the line produces a characteristic frequency which is broadcast by its antenna 13. A series of such oscillator systems may be distributed at unequal intervals for giving a definite characterized radiation over a certain area. Each oscillator may provide a radiation which is different from any other both as to frequency and amplitude for indicating geographical position and direction of fiight.

Figs. 12, 13, 14, 15, and 16 show various types of radiating antennae for high frequency currents transmitted over power line or telephone conductors. As these systems are fed from the power line itself, they broadcast energy at a constant frequency, but may be adjusted to provide varying amplitudes. Fig. 12 shows a single loop 15, while Fig. 13 shows a double loop I6. Fig. 14 shows a twisted vertical antenna 11, while the vertical System18 of Fig. 15 is formed into an L type arrangement. Fig. 16 has an. elongated coil positioned around the power line conductor and insulated therefrom by insulators 8|. The coil 80 may be connected to the line at pole 80' to aid in supporting the coil.

Fig. 17 shows a characterized radiating point similar to the one of Fig. 8, but which has a tuning coil 83 in series with a gap 84, and condenser for obtaining sharper tuning of a harmonic of the discharge across the gap.

Figs. 18 and 19 show auxiliary antennae systems 81 and. 8B paralleling the power line, to obtain stronger radiation than that obtainable from the power linesalone. These auxiliary wires may be of different lengths, to obtain a different amplitude characteristic, while the gap 89 may generate different radiating frequencies for broadcasting by the antenna 88.

The above disclosed systems are especially applicable to field characterizations involving transmission only. The combination transmitting and receiving system shown in Fig. 20, however, is of a transmitter T2, energized from the power lines, and used for broadcasting definite communication signals to aircraft. A filter is employed to permit only-the power frequency being supplied to the transmitter. which may be of any well known type. The transmitter employs antenna 9| fed through a transformer 92. An associate receiver system 94 receives both its power and signaling currents originating from vide them with information as to weather conditions to be encountered. This communication apparatus may be entirely supplied from the power circuits traversing the country, providing a simple solution for maintaining such apparatus at regular intervals over definite routes.

It will be obvious to those skilled in the art that many modifications may be made in the systems and apparatus above disclosed, but it is to beunderstood that such modifications are contemplated to be within the scope of the appended claims.

What is claimed is:

1. A system for characterizing an aerial route with electromagnetic waves comprisinga power line traversing a definite area, said power line transmitting power energy of definite voltage and at a comparatively low frequency, means for generating and applying to said power line currents having higher frequencies than the frequencies of said power energy, and means at periodic predetermined points along said power line for changing the radiation of said line from its normal radiation, said means including conductors looped about said power line conductors which change the direction of the magnetic field set up by said currents.

2. A system for electro-magnetically characterizing aerial space comprising a power line traversinga certain area, said power line transmitting energy of a comparatively 'low frequency, means connected to said line for generating and applying to said line energy of higher frequencies than the energy of said power line, a tuned circuit included in said last mentioned means for predetermining the frequencies generated and applied to said line, and means for increasing the effective radiation of said predetermined frequencies into the space adjacent said line at the point of connection of said generated means with said line, said means including conductors about said line to determine the direction of the magnetic field set up by said energy of predetermined frequencies.

ALEXANDER MCLEAN NICOLSON. 

